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Biomedical subjects

Enca Martin-Rendon

Publications and source records attributed to Enca Martin-Rendon.

8 recordsLinked to original sources
PubMed2003

Protein glycosylation in disease: new insights into the congenital muscular dystrophies.

Glycosylation is the most frequent modification of proteins and is important for many ligand-receptor interactions. Recently, defects in protein glycosylation have been linked to several forms of congenital muscular dystrophy that are frequently associated with brain abnormalities. Muscle-eye-brain disease and Walker-Warburg syndrome are caused by mutations in enzymes involved in O-mannosylation, whereas Fukuyama congenital muscular dystrophy and congenital muscular dystrophy type 1C are caused by mutations in genes that encode putative glycosyltransferases. The common factor in these disorders is defective processing and maturation of a protein called alpha-dystroglycan. This is thought to disrupt the link between alpha-dystroglycan and components of the extracellular matrix, and result in muscle disease and, in many cases, a neuronal-migration disorder.

Animals↗
PubMed2003

Long-term replacement of a mutated nonfunctional CNS gene: reversal of hypothalamic diabetes insipidus using an EIAV-based lentiviral vector expressing arginine vasopressin.

Due to the complexity of brain function and the difficulty in monitoring alterations in neuronal gene expression, the potential of lentiviral gene therapy vectors to treat disorders of the CNS has been difficult to fully assess. In this study, we have assessed the utility of a third-generation equine infectious anemia virus (EIAV) in the Brattleboro rat model of diabetes insipidus, in which a mutation in the arginine vasopressin (AVP) gene results in the production of nonfunctional mutant AVP precursor protein. Importantly, by using this model it is possible to monitor the success of the gene therapy treatment by noninvasive assays. Injection of an EIAV-CMV-AVP vector into the supraoptic nuclei of the hypothalamus resulted in expression of functional AVP peptide in magnocellular neurons. This was accompanied by a 100% recovery in water homeostasis as assessed by daily water intake, urine production, and urine osmolality lasting for a 1-year measurement period. These data show that a single gene defect leading to a neurological disorder can be corrected with a lentiviral-based strategy. This study highlights the potential of using viral gene therapy for the long-term treatment of disorders of the CNS.

Animals↗
PubMed2002

Functional requirements for fukutin-related protein in the Golgi apparatus.

Two forms of congenital muscular dystrophy (CMD), Fukuyama CMD and CMD type 1C (MDC1C) are caused by mutations in the genes encoding two putative glycosyltransferases, fukutin and fukutin-related protein (FKRP). Additionally, mutations in the FKRP gene also cause limb-girdle muscular dystrophy type 2I (LGMD2I), a considerably milder allelic variant than MDC1C. All of these diseases are associated with secondary changes in muscle alpha-dystroglycan expression. To elucidate the function of FKRP and fukutin and examine the effects of MDC1C patient mutations, we have determined the mechanism for the subcellular location of each protein. FKRP and fukutin are targeted to the medial-Golgi apparatus through their N-termini and transmembrane domains. Overexpression of FKRP in CHO cells alters the post-translational processing of alpha- and beta-dystroglycan inhibiting maturation of the two isoforms. Mutations in the DxD motif in the putative active site of the protein or in the Golgi-targeting sequence, which cause FKRP to be inefficiently trafficked to the Golgi apparatus, did not alter dystroglycan processing in vitro. The P448L mutation in FKRP that causes congenital muscular dystrophy changes a conserved amino acid resulting in the mislocalization of the mutant protein in the cell that is unable to alter dystroglycan processing. Our data show that FKRP and fukutin are Golgi-resident proteins and that FKRP is required for the post-translational modification of dystroglycan. Aberrant processing of dystroglycan caused by a mislocalized FKRP mutant could be a novel mechanism that causes congenital muscular dystrophy.

Amino Acid Sequence↗
PubMed2002

Multicistronic lentiviral vector-mediated striatal gene transfer of aromatic L-amino acid decarboxylase, tyrosine hydroxylase, and GTP cyclohydrolase I induces sustained transgene expression, dopamine production, and functional improvement in a rat model of Parkinson's disease.

Parkinson's disease (PD) is a neurodegenerative disorder characterized by the selective loss of dopaminergic neurons in the substantia nigra. This loss leads to complete dopamine depletion in the striatum and severe motor impairment. It has been demonstrated previously that a lentiviral vector system based on equine infectious anemia virus (EIAV) gives rise to highly efficient and sustained transduction of neurons in the rat brain. Therefore, a dopamine replacement strategy using EIAV has been investigated as a treatment in the 6-hydroxydopamine (6-OHDA) animal model of PD. A self-inactivating EIAV minimal lentiviral vector that expresses tyrosine hydroxylase (TH), aromatic amino acid dopa decarboxylase (AADC), and GTP cyclohydrolase 1 (CH1) in a single transcription unit has been generated. In cultured striatal neurons transduced with this vector, TH, AADC, and CH1 proteins can all be detected. After stereotactic delivery into the dopamine-denervated striatum of the 6-OHDA-lesioned rat, sustained expression of each enzyme and effective production of catecholamines were detected, resulting in significant reduction of apomorphine-induced motor asymmetry compared with control animals (p < 0.003). Expression of each enzyme in the striatum was observed for up to 5 months after injection. These data indicate that the delivery of three catecholaminergic synthetic enzymes by a single lentiviral vector can achieve functional improvement and thus open the potential for the use of this vector for gene therapy of late-stage PD patients.

Animals↗
PubMed2002

New methods to titrate EIAV-based lentiviral vectors.

Ideally, gene transfer vectors used in clinical protocols should only express the gene of interest. So far most vectors have contained marker genes to aid their titration. We have used quantitative real-time PCR to titrate equine infectious anemia virus (EIAV) vectors for gene therapy applications. Viral RNA was isolated from vector preparations and analyzed in a one-step RT-PCR reaction in which reverse transcription and amplification were combined in one tube. The PCR assay of vector stocks was quantitative and linear over four orders of magnitude. In tandem, the integration efficiency of these vectors has also been determined by real-time PCR, measuring the number of vector genomes in the target cells. We have found that these methods permit reliable and sensitive titration of lentiviral vectors independent from the expression of a transgene. They also allow us to determine the integration efficiency of different vector genomes. This technology has proved very useful, especially in the absence of marker genes and where vectors express multiple genes.

Animals↗
PubMed2002

Intermediate filaments and the function of the dystrophin-protein complex.

Intermediate filament (IF) proteins and the dystrophin-associated protein complex (DPC) play important roles in cardiac and skeletal muscle. Both systems are mutated in several different forms of inherited muscular dystrophy and cardiomyopathy. Recently two articles have been published that propose a physical link between the DPC and the IF network in muscle. Two novel IF proteins, syncoilin and desmuslin, have been identified as binding partners for the dystrophin-associated protein, alpha-dystrobrevin, in muscle. These novel interactions suggest that alpha-dystrobrevin may tether the IF protein network to the DPC. Mice lacking alpha-dystrobrevin develop muscular dystrophy without perturbing the assembly of the DPC at the muscle membrane, suggesting the involvement of other non-DPC proteins in the disease. The interaction between the DPC and the IF network may be disrupted in patients with Duchenne muscular dystrophy and in mice lacking alpha-dystrobrevin.

Cytoskeletal Proteins↗